This invention relates to a storage and mixing silo for bulk material wherein a common silo body has a storage compartment and, in the lower part of the silo body, a mixing compartment in the form of an annular chamber which is smaller than the storage compartment. The mixing compartment communicates with the storage compartment through a material inlet opening provided in the inner boundary wall of the annular chamber and has at least one material outlet opening. The silo body includes means for the pneumatic aeration, particularly of the base, of the storage and mixing compartments.
In one known storage and mixing silo for bulk material (DE-OS No. 27 27 499), there is a central mixing compartment which, in its peripheral wall, has a number of material inlet openings through which it communicates with the surrounding base of the storage compartment. In addition, an annular inspection passage is arranged both around the peripheral wall of the mixing compartment and within the body of the silo to enable the various parts of the silo to be monitored and operated. The arrangement of the annular passage around the mixing compartment involves undesirable capital outlay without any possibility of the mixing effect being influenced by the provision of this annular passage alone.
In another known embodiment (DE-OS No. 23 36 984), the base region of the storage compartment is surrounded by an outer annular passage of which the inner boundary wall forms the lower storage ramp of the storage compartment. This annular passage communicates peripherally with the storage compartment through several material inlet openings. As is evident in particular from the measures taken here to transfer the material from the storage compartment to the annular passage, the sole object of this known arrangement is to obtain particularly favourable emptying of the storage compartment. If it is desired to obtain a particular mixing or homogenising effect during the emptying of the storage compartment through the annular passage, a separate mixing chamber has to be fitted which of course involves increased capital outlay.
In a mixing silo known from DE-AS No. 24 17 468, the mixing chamber is formed by a type of annular chamber which is essentially an axial lower extension of the storage compartment from which it is separated solely by a flat, funnel-like base. In the center of this annular chamber, there is a vertical hollow column which, at one end, supports the center of the base of the storage compartment and, at its other end, comprises a central material inlet opening connecting the storage compartment to the annular mixing compartment. In addition, a transverse partition is arranged inside this hollow column, so that the material outlet which is also centrally arranged at the lower end of this hollow column is covered overhead.